Fort Lewis College 1 Charles Hakes Fort Lewis College 2 Charles Hakes Fort Lewis College 3 Dead Stars Charles Hakes Fort Lewis College 4 Outline Test 3 Friday Lab Notes Dead Stars ID: 422126
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Charles HakesFort Lewis College
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Charles Hakes
Fort Lewis College2Slide3
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“
Dead
”
StarsSlide4
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Outline
Test 3
Friday
Lab Notes
Dead (?) Stars
Review (?)Slide5
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Test 3
Review Spectroscopy (Wein, Stefan) and Doppler Shift
The Sun (structure, fusion)
Magnitude
Parallax
Interstellar Medium
Stellar Evolution
Dead StarsSlide6
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Lab Notes
Constellation presentation this week
Telescope lab
Star identification
lab?
Observatory Field Trip?
ParallaxSlide7
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More Precisely 12-1
The Cycle of Stellar EvolutionSlide8
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Supernovae
On-line images
Supernova in M 74
http://www.rochesterastronomy.org/sn2003/n628s2.jpg
Supernova in NGC 1448
http://members.optushome.com.au/edobosz/images/1448_sn.jpg
Supernova in NGC 3169
http://www.astrooptik.com/Bildergalerie/PolluxGallery/NGC3169.htm
Supernova in NGC 3190
http://www.astrooptik.com/Bildergalerie/PolluxGallery/NGC3190.htm
Supernova in NGC 5965
http://www.nordita.dk/~dahle/ngc5965_sub.gif
Supernova in NGC 918
http://antwrp.gsfc.nasa.gov/apod/ap091112.htmlSlide9
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Chapter 13
What is left after a Supernova?Slide10
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Figure 12.21
Supernova RemnantsSlide11
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Figure 13.1
Neutron Star - from a type II Supernova
typically ~20 km diameter
mass > M
sun
thimbleful would weigh 10
8
tons
rotate very quickly
have very strong magnetic fields.Slide12
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Figure 13.2
Pulsar Radiation
The first observed neutron star was a pulsar
Neutron stars rotate VERY quickly.Slide13
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Figure 13.3
Pulsar Model
lighthouse model - if the beam sweeps past the Earth, we see a pulse.Slide14
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At a distance of 1 A.U., which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.Slide15
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At a distance of 1 A.U., which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.Slide16
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At the surface of the object, which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.Slide17
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At the surface of the object, which would have the greatest gravitational force?
A) A 1 solar mass main sequence star
B) A 1 solar mass white dwarf
C) A 1 solar mass neutron star
D) They all have the same force.Slide18
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A neutron star cannot be more than 3 M
sun
.Slide19
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A neutron star cannot be more than 3 M
sun
.
Surface gravity will become so great that not even light can escape. (Escape velocity > c)Slide20
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A neutron star cannot be more than 3 M
sun
.
Surface gravity will become so great that not even light can escape. (Escape velocity > c)
Stars that began with > 25 M
sun
will probably become
black holes
.Slide21
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Black Holes
Can black holes be made of things other than neutron stars?
Any object of any mass has a radius that if it is compressed below that radius, light cannot escape.
This is called the Schwarzschild radius.
r
S
= 3km x M(solar masses)Slide22
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Black Holes
Example Schwarzschild radii :
Sun = 3km
3M
solar
Core = 9km
Jupiter = 3mSlide23
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Black Holes
Exercise - calculate the size required to compress a 70 kg person to make a black hole.
recall:
r
S
= 3km x M(solar masses)Slide24
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Black Holes
Example Schwarzschild radii :
Sun = 3km
3M
solar
Core = 9km
Jupiter = 3m
Earth = ~1cm
Person = ~1x10
-25
m
M
observable universe
= ~r
observable universeSlide25
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If the Sun were suddenly replaced by a one solar mass black hole:
A) we would immediately escape into deep space, driven out by its radiation.
B) our clocks would all stop.
C) life here would be unchanged.
D) we would still orbit it in a period of one year.
E) all terrestrial planets would fall in immediately.Slide26
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If the Sun were suddenly replaced by a one solar mass black hole:
A) we would immediately escape into deep space, driven out by its radiation.
B) our clocks would all stop.
C) life here would be unchanged.
D) we would still orbit it in a period of one year.
E) all terrestrial planets would fall in immediately.Slide27
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Practice Problem
You observe a binary star system where the two stars are exactly the same temperature. The diameter of one star is 1.2 times the diameter of the second star. How many times more energy is emitted by the brighter star?Slide28
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Practice Problem
You observe a binary star system where the two stars are exactly the same temperature. The diameter of one star is 1.2 times the diameter of the second star. How many times more energy is emitted by the brighter star?
A. 1.095x B. 1.2x C. 1.44x D. 2xSlide29
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Practice Problem
You observe a binary star system where the two stars are exactly the same size. One star is 5500 K. The other star is 6100 K. How many times more energy is emitted by the brighter star?Slide30
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Practice Problem
You observe a binary star system where the two stars are exactly the same size. One star is 5500 K. The other star is 6100 K. How many times more energy is emitted by the brighter star?
A. 1.11x B. 1.23x C. 1.51x D. 600xSlide31
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Review QuestionsSlide32
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An ordinary star becomes a Red Giant when:
A) A white dwarf companion star goes nova
B) There is no Hydrogen remaining in the star
C) Nutrino oscillations drive the outer layers
D) The core becomes almost entirely HeliumSlide33
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An ordinary star becomes a Red Giant when:
A) A white dwarf companion star goes nova
B) There is no Hydrogen remaining in the star
C) Nutrino oscillations drive the outer layers
D) The core becomes almost entirely HeliumSlide34
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A main sequence star of 19 solar masses will eventually be a:
A) A brown dwarf
B) A white dwarf
C) A type I supernova
D) A type II supernovaSlide35
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A main sequence star of 19 solar masses will eventually be a:
A) A brown dwarf
B) A white dwarf
C) A type I supernova
D) A type II supernovaSlide36
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A supernova is observed with very little H in the spectrum. It is most likely a:
A) type I
B) type II
C) type III
D) not enough informationSlide37
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A supernova is observed with very little H in the spectrum. It is most likely a:
A) type I
B) type II
C) type III
D) not enough informationSlide38
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A source of light is approaching us at 3,000 km/s. All its waves are:
A) Red shifted by 1%
B) Blue shifted by 1%
C) Not affected, as c is constant in all reference frames.
D) Red shifted out of the visible into the infrared
E) Blue shifted out of the visible into the ultravioletSlide39
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A source of light is approaching us at 3,000 km/s. All its waves are:
A) Red shifted by 1%
B) Blue shifted by 1%
C) Not affected, as c is constant in all reference frames.
D) Red shifted out of the visible into the infrared
E) Blue shifted out of the visible into the ultravioletSlide40
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How could you determine the temperature of the photosphere of the Sun?
A) only direct spacecraft measurement
B) Newton
’
s Law
C) Stefan
’
s Law
D) Wein
’
s lawSlide41
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How could you determine the temperature of the photosphere of the Sun?
A) only direct spacecraft measurement
B) Newton
’
s Law
C) Stefan
’
s Law
D) Wein
’
s lawSlide42
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If a star has a parallax of 0.05
”, then its distance must be
A) 5 light years.
B) 5 parsecs
C) 20 light years.
D) 20 parsecs.
E) 200 parsecsSlide43
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If a star has a parallax of 0.05
”, then its distance must be
A) 5 light years.
B) 5 parsecs
C) 20 light years.
D) 20 parsecs.
E) 200 parsecsSlide44
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Assume your naked eye limiting magnitude is 4. With a 70mm diameter telescope (100x area of your pupil) which object would be barely visible?
A) Seventh magnitude Titan, Saturn
’
s largest moon.
B) Eighth magnitude Uranus.
C) Ninth magnitude Barnard
’
s Star
D) Eleventh magnitude Tethys, another Saturn moon
E) Thirteenth magnitude PlutoSlide45
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Assume your naked eye limiting magnitude is 4. With a 70mm diameter telescope (100x area of your pupil) which object would be barely visible?
A) Seventh magnitude Titan, Saturn
’
s largest moon.
B) Eighth magnitude Uranus.
C) Ninth magnitude Barnard
’
s Star
D) Eleventh magnitude Tethys, another Saturn moon
E) Thirteenth magnitude PlutoSlide46
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On the H-R diagram, red supergiants like Betelguese lie:
A) top right
B) top left
C) about the middle
D) lower left
E) on the coolest portion of the main sequenceSlide47
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On the H-R diagram, red supergiants like Betelguese lie:
A) top right
B) top left
C) about the middle
D) lower left
E) on the coolest portion of the main sequenceSlide48
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From inside out, which is the correct order?
A) core, convective zone, radiative zone
B) photosphere, radiative zone, corona
C) radiative zone, convective zone, chromosphere
D) core, chromosphere, photosphere
E) convective zone, radiative zone, granulationSlide49
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From inside out, which is the correct order?
A) core, convective zone, radiative zone
B) photosphere, radiative zone, corona
C) radiative zone, convective zone, chromosphere
D) core, chromosphere, photosphere
E) convective zone, radiative zone, granulationSlide50
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If Vega is apparent magnitude zero, and Deneb first magnitude, then
A) Vega is about 100x brighter than Deneb..
B) Deneb is one magnitude brighter than Vega.
C) Vega appears 2.5x brighter than Deneb.
D) Deneb must be a main sequence star, and Vega a giant.
E) Vega must be 2.5x more luminous than Deneb.Slide51
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If Vega is apparent magnitude zero, and Deneb first magnitude, then
A) Vega is about 100x brighter than Deneb..
B) Deneb is one magnitude brighter than Vega.
C) Vega appears 2.5x brighter than Deneb.
D) Deneb must be a main sequence star, and Vega a giant.
E) Vega must be 2.5x more luminous than Deneb.Slide52
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Three Minute Paper
Write 1-3 sentences.
What was the most important thing you learned today?
What questions do you still have about today
’
s topics?